1. Field of the Invention
This invention principally relates to a machine for applying subatmospheric pressure through a filter to suck particulate material, fluent en masse, from a hopper laterally into a non-rotatable measuring chamber of presettable volume and, after the chamber is filled, applying super-atmospheric pressure through the filter to force the particulate material downwardly out of the chamber through a nozzle into a receptacle. Optionally, a discharging pressurized pulse is followed by a brief more highly pressurized pulse to purge the filter. An ancillary feature of the invention is concerned with ready interchangeability of the machine from the dispensing of liquid to that of particulate material and vice versa.
2. Description of Related Art
Equipment for filling receptacles with liquid and with flowable dry particulate material is quite old in the art and has been available for many years. Nevertheless, in many fields they are susceptible to improvements. Thus, in the pharmaceutical field, where such machines are widely used, it is particularly desirable for the parts of the machines, which contact pharmaceutical materials that are to be packaged, to be as few in number and as small in size as possible and to be readily accessible for cleaning and sterilization, and refinements are constantly being designed to this end. Furthermore, and especially in pharmaceutical filling machines, it is quite advantageous for the machines to maintain a high degree of accuracy. The same aspiration exists in non-pharmaceutical fields and, there too, the quest as yet has not been satisfied.
Typical prior art filling machines are manufactured by PERRY INDUSTRIES, INC. of Hicksville, N.Y., being known as PERRY ACCOFILS, a registered mark, these being the series 0, 1, and 2, Models CMR 124; and CMR 2. These machines are continuous motion rotary powder fillers, purported to be designed for high-speed, fully automatic, powder filling. They include a hopper which leads to a rotary filling wheel that turns about a horizontal axis continuously through successive 360.degree. cycles. The wheel includes plural cylinders, known as ports, each terminating at an open mouth on the periphery of the wheel. Each port includes an internal filter-containing head. The heads can be set in any desired axial positions within the ports to define between each head and the periphery of the wheel a chamber of settable volume. As the wheel rotates, the cavities of the ports are subjected one after another, sequentially, to sub-atmospheric and supra-atmospheric pressure. When a port is erect, with its mouth uppermost, its mouth is exposed to the hopper. At the same time, suction is applied beneath the filter-head and thence to this port to draw the product, which is powder, from the hopper into the port. As the wheel rotates, this port leaves the hopper and passes beneath a doctor blade which brushes excess product off the top of the port while vacuum is maintained on the filled port. Continued rotation of the wheel brings the port to a downwardly extending position over a transition funnel that leads to a container for the powder. At the transition funnel, a puff of pressurized air is applied above the back of the filter-head and thence to the powder in the measuring chamber to eject the powder from the port into the funnel and thereupon into the container. Upon further rotation of the wheel, a more highly pressurized pulse of purge air is applied to the back of the filter-head to clean the filter. Finally, the port returns to its erect position for a refill from the hopper.
The cooperation of the port as it enters into and leaves alignment with the hopper discharge opening produces a valve-like action which, on the one hand, permits and, on the other hand, cuts off flow of powder from the hopper to the port. The same type of action is experienced between the port and the transition funnel upon discharge of powder from the port. In both instances, a pair of relatively moving parts move past one another in shear to cut off flow of powder and in doing so subject the last particles of powder flowing through the valve to a shearing action between two relatively moving surfaces. This shearing action further reduces the size of the particles caught which has certain deleterious effects. These fragmented particles find their way into the interstices of the machine where they interfere with relative movement of machine parts; increase the power requirements of the machine; increase the wear to which the machine is subjected; and, to some extent, become mixed in with the powder which the machine is handling which may adversely affect the reaction created by the powder if used pharmeceutically on a patient, as by unduly increasing the speed of reaction to an unpredictable extent. A further disadvantageous effect is that the fragmented particles roll between the opposing surfaces which are passing one another in shear and scrape off tiny detritus from these surfaces which mix in with the powder to contaminate the same.
The containers are fed in line to a star wheel that transfers them to a rotary dial plate which passes the containers, each under a transition funnel, to a filling station where they are lifted into coupling relationship to a discharge outlet with an associated transition funnel and are filled. Finally, the filled containers are closed and transferred to an exit line. All of the filter-heads can be adjusted simultaneously in their ports. Other types of line filling equipment also have been employed in these machines.
The machine is capable of filling up to 300 containers per minute with from 50 mg. to 36 ozs. of product. There are a relatively large number of parts and the machine is, therefore, costly to maintain and keep in good working condition. Many of the parts that touch the powder, are exposed, making the machine difficult to keep clean and, for pharmaceutical products, difficult to sterilize. The machine allows the product to escape at various points, with resultant loss of product which is uneconomical and unsanitary and creates a bad working environment. Because of the multiple adjustments of the several ports, such adjustments, although interlocked, are not easy to make.
Another problem with the Perry machine is that the agitator is a rotary member which is driven by a shaft that extends through the side of the hopper in a bearing. As the shaft turns, the bearing wears and in so doing discharges a thin, but steady flow of particulate material worn from the seal. This material is permitted to flow into the powder being handled by the machine where it may contaminate the same.
It would be a considerable boon to the industry if a filling machine were provided that was of far simpler and less costly construction.
PERRY INDUSTRIES, INC. also manufactures a line of equipment designed to fill only liquids into containers. These are separate machines which cannot be converted to switch from powder to liquid and vice versa; while these liquid fillers may be suitable for the particular purposes to which they are addressed, they are not suitable for the purposes of the present invention as hereinafter described.